Human red blood cell stroma: an alternative to traditional allogeneic adsorption methods

Allogeneic adsorption (alloadsorption) involves incubating an aliquot of patient plasma with red blood cells (RBCs) of a known phenotype to facilitate removal of autoantibodies and allow for detection of remaining, potentially clinically significant alloantibodies. Alloadsorptions are routinely performed using fresh or frozen donor RBCs having particular Rh and Kidd phenotypes, and are usually enzyme or ZZAP treated before adsorptions. RBC stroma would provide a method to prepare large amounts of adsorption material that may be stored frozen and used when needed.

A total of 309 samples were presented to our institutions (American Red Cross, Southwest Region Texas laboratories) with serologic positive IgG autoantibodies, had allogeneic RBC stromal adsorptions performed, and underlying alloantibodies identified. After papain treatment of RBCs from group O, K- individuals who were R₁ R₁ , R₂ R₂ , and rr where at least one individual was Jk(a+b-) and one individual Jk(a-b+), stroma was prepared using digitonin digestion of the RBC membrane. Large amounts of stroma could be obtained and were aliquoted and frozen at -18°C or less for up to 2 years.

One hundred seventeen of 309 (38%) samples demonstrated alloantibodies following stromal alloadsorptions. Twenty-two different alloantibodies were identified in the stroma-adsorbed plasma, with an average of two stromal adsorptions resolving the autoantibody reactivity. The specificities of alloantibodies underlying the autoantibody included those in the Rh system (112), Kell system (24), Duffy system (14), Kidd system (30), MNS system (19), Lutheran system (2), and Diego system (2).

Successful removal of autoantibody using RBC stromal adsorption was obtained in 308 samples and allowed for the identification of underlying alloantibodies in 117 samples. Preparation and use of RBC stroma should significantly benefit immunohematology reference laboratories in their antibody investigations.